Missing items in UIcollectionview on iOS7 - ios

Question

I'm created a collection view of sticker like Facebook Message and add auto layout for them in storyboard. Its ok on iOS 8. But when I'm run its on iOS 7 all items in collection view are disappeared. Can someone tell me what's wrong with my code and how to solve this problem?
Here is my code:
#pragma mark - UICollectionViewDataSource
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{
return stampCategorySelected.templetes.count;
}
// The cell that is returned must be retrieved from a call to -dequeueReusableCellWithReuseIdentifier:forIndexPath:
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
StampsCollectionViewCell *cell = (StampsCollectionViewCell*) [collectionView dequeueReusableCellWithReuseIdentifier:kStampCellIdentifier forIndexPath:indexPath];
NSString *imgPath = [NSString stringWithFormat:#"%#/%#", STAMP_PATH, stampCategorySelected.templetes[indexPath.row]];
cell.stamp.image = [UIImage imageNamed:imgPath];
//Set page control count
int pageCount = floor(collectionView.contentSize.width / collectionView.frame.size.width) + 1;
_pagesControl.numberOfPages = pageCount;
return cell;
}
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath{
return CGSizeMake(PC_Width/4, PC_Width/4);
}
#pragma mark - UICollectionViewDelegate
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{
_clipart.kind = #"stamp";
_clipart.clipartid = [stampCategorySelected.templetes[indexPath.row] stringByDeletingPathExtension];
_clipart.clipartPath = stampCategorySelected.templetes[indexPath.row];
_clipart.index = 0;
_clipart.center = [Utilities arrayFromPoint:DEFAULT_CENTER];
UIImage * clipartImage = [UIImage imageWithContentsOfFile:[NSString stringWithFormat:#"%#/%#", STAMP_PATH, stampCategorySelected.templetes[indexPath.row]]];
if (!clipartImage) {
clipartImage = [UIImage imageNamed:[STAMP_PATH stringByAppendingPathComponent:stampCategorySelected.templetes[indexPath.row]]];
}
_clipart.size = #[#(_templateSize.width/5), #((clipartImage.size.height/clipartImage.size.width)*_templateSize.width/5)];
_clipart.maxscale = 1;
_clipart.scale = 1.0f;
_clipart.angle = 0.0f;
FSLog(#"Selected clipart: %#", _clipart);
[_delegate stampViewController:self didSelectStamp:_clipart];
[self dismiss:nil];
}